re: Contemplating our Planet in this Vast Universe

All of the things you mentioned are pretty necessary for life to thrive, so you might say that if complex life is going to exist in the universe, it was bound to be on a planet that had all of those things.

Considering the relative sizes and distances of the sun and the moon is where things get a bit more freaky. The sun's diameter is roughly 400 times that of the moon. It is also roughly 400 times further away from the earth. The result is that, from our vantage, they both appear the same size in the sky. This is what makes total eclipses possible. This congruence of the two dominant objects in our sky is not at all necessary for complex life to exist. If it is only a coincidence, it is one of staggering unlikeliness.